This proposal is to extend the long-term follow-up of the San Luis Valley Diabetes Study (SLVDS), a unique biethnic (Hispanic and non-Hispanic white) rural cohort of subjects originally examined in 1984-1988, and reexamined every two to four years since. This renewal is proposed to understand the heterogeneity that exists among subjects at risk for NIDDM, especially as related to insulin secretion and resistance defects. Sufficient numbers of persons will be investigated from the time when they had normal or impaired glucose tolerance to identify homogeneous subgroups of those progressing to NIDDM. This will allow identification of the earliest defects and risk factors that underlie NIDDM, with minimal misclassification. The SLVDS will continue to serve as a population laboratory for funded and proposed additional studies on diabetes, cardiovascular and other chronic diseases. The SLVDS is one of only two population-based studies of these important conditions in the Hispanic minority population, and the only on located in a rural area. The specific aims are as follow: 1. Reexamine the 1,044 eligible non-diabetic cohort members 9-13 years after baseline to identify the incidence of NIDDM, its heterogeneity, and risk factors, and specifically to: a. Identify population subgroups with more homogeneous phenotypic patterns of insulin secretion, insulin resistance, risk factors, and glucose intolerance; b. Determine preventable lifestyle factors that act at different stages of glucose intolerance (normal to IGT, IGT to NIDDM), and on specific homogeneous subgroups defined by risk factor combinations; c. Determine if patterns of insulin resistance and insulin secretion from multiple oral glucose tolerance tests (OGTT) over time predict more precise measures of secretion and resistance from FSIGT data available on a subset of the SLVDS cohort (N=258); d. Rule out the presence of IDDM, among persons with incident diabetes by measuring beta-cell autoantibodies (to GAD65, insulin and ICA512); 2. Continue biennial telephone and mail surveillance for key clinical outcomes (diabetes, cardiovascular disease, cause-specific mortality) in the total cohort; 3. Provide phenotypically homogeneous subgroups of individuals with insulin resistance and/or insulin secretion defects for separately funded